Absorption refrigeration system including condenser pressure control means



W. W. WILLIAMS March 9, 1948. 2,437,577

ABSORPTION REFRIGERATION SYSTEM INCLUDING CONDENSER PRESSURE CONTROL MEANS Original Filed Aug. 3, 1940 2 Sheets- Sheet 1 MalCh 9, 1948. W` W, W|| |AMS 2,437,577 4 ABSORPTION REFRIGERATION SYSTEM INCLUDING CONDENSER PRESSURE CONTROL MEANS Orlglnal Filed Aug 5, 1940 2 Sheets-Sheet 2 Patented Mar. 9, 1948 ABSORPTION REFRIGERATION SYSTEM INCLUDING CONDENSER PRESSUR CONTROL MEANS Walter W. Williams, Bloomington, Ill., assigner to Eureka Williams Corporation, a corporation of Michigan Original application August 3, 1940, Serial No.

Divided and this application March 27, 1944, Serial No. 528,281

7 Claims. (Cl. 62-5) This application is a division of my prior application Serial No. 350,993, filed August 3, 1940, for Refrigerating apparatus, which matured into Patent No. 2,356,639 on Aug. 22, 1944.

This invention relates to a refrigeration apparatus, and more particularly to a refrigerating apparatus of the absorption type.

More particularly, this invention relates to the provision of a new and improved absorption refrigerating apparatus in which a fluid, such as water or air, may be chilled to produce the desired refrigeration. herein disclosed is adapted for use primarily in air conditioning systems or'refrigerating systems of a domestic or commercial type, and it is an object thereof to provide means for regulating the transfer of solvent and refrigerant in a refrigerating system whereby optimum heat transfer and econ-omy result.

Further and additional objects will appear from the following description, the -appended drawings, and the accompanying claims] An absorption refrigerating apparatus constructed in accordance with one embodiment of this invention comprises an absorber in which the refrigerant vapor, such as methyleneychloride, is absorbed by a solvent, such as the dimethyl ether of tetraethylene glycol; a genera- The apparatus or system tor or heater in which the refrigerant is distilled from the strong solution; a heat exchanger for eifecting the transfer of heat between the hot, weak, solvent solution flowing from the heater to the absorber and the cool, strong'solution of refrigerant dissolved in the solvent flowing from the absorber to the heater; a condenser in which the refrigerant vapor from the heater is condensed to a liquid; and la chiller into which the refrigerant liquid is expandedand through which the fluid to be cooled is passed.

In the operation of the above apparatus, the gaseous refrigerant is dissolved in the liquid solvent in the absorber, and the mixture of strong solution is circulated through the heat exchanger, to the generator. Within the generator the strong solution is subjected to elevated temperatures, causing the refrigerant to separate from the solvent in the form of a vapor. The refrigerant vapor is 'passed to a condenser where it iscooled and condensed to a liquid, and the condensed liquid is expanded through an expansion valve and passed to the chilling unit. The-expansion valve may be float-controlled so that the amount of liquid refrigerant passing therethrough into the chiller is dependent upon the liquid level of refrigerant within the chiller, and

a constant level may thereby be maintained. The refrigerant vapors formed in the chlller are then recirculated from the chiller unit to the absorber wherein they are re-absorbed by the weak solution of solvent which is withdrawn from the heater or generator, returned through the heat exchanger, strained and reintroduced into the absorber.

Means are also provided for returning any small quantities of solvent that may inadvertently collect in the chlller. The rate of ow of strong solution pumped from the absorber may be Vcontrolled by a specially constructed naat valve which will be hereinafter more fully described. Also the amount of flow of the cooling water through coils in the absorber and the condenser may be regulated by an automatic pressure-controlled valve which operates to automatically maintain the high side pressure in the apparatus at a substantially constant predetermined value regardless of the temperature of the cooling Water; The pressure on the high side of the system is about atmospheric or slightly above, and the pressure `of the low side is between about 20 to 25 inches of mercury vacuum when methylene chloride and the dimethyl4 ether of tetraethylene glycol are used as the refrigerant and solvent, respectively.

For la more complete understanding of this invention, reference will now be had to the drawings, in which Figure 1 is a` diagrammatic view of a complete refrigerating apparatus constructed in accordance with one embodiment of this invention;

Fig. 2 is a side elevational view, partially in A section, of a valve employed in the system shown in Fig. 1 which is used to regulate the amount of cooling water passing through the coils of the condenser.

Referring now mme particularly to Fig. 1, itis believed that the refrigerating apparatus there shown can best be understood by tracing the circulation of the various fluids therein.

The strong solution of solvent and refrigerant is removed from the sump I 2 of an absorber I4 by a duplex pump I6, driven by any suitable means (not shown). The pump I6 is preferably one of the'impositive displacement type. such as a centrifugal pump, wherein the volume oi' iluid pumped through it may be controlled by the back pressure on the pump. The solution is discharged from the pump through a conduit I8 to a floatcontrol valve 20 having conduits 22 and'24 associated therewith leading to a conduit below the sump I2 and to the absorber I4, respectively,

which sem m maintain a level of liquid m the l valve the same as the level in the sump I2. The

float-controlled valve which is fully described inabsorber. and is adiusted to prevent the level of fluid in the sump from falling below a predetermined level, whereby cavitation of the pump is l prevented.

From the float valve 20 the strong solution passes through a conduit 26, a heat exchanger 28, and a conduit 30int'o th manifold 38 of a heater vor generator 32. The generator comprises a steam jacket 34 having disposed therein a piurality of coils 36 fed from the manifold 38, each of which coils discharges into an inner receptacle 40 of the heater 32. The steam chamber 34 is supplied with live steam from the steam coils 42 of a boiler 43, which boiler isheated by a gas or oil burner 44. The steam passes from the steam coils 42 into a header 45 and thence through the duct 46 into the steam chamber 34, the condensate returning back to the header 45 through conduit 48. A safety valve 60 is provided for the steam chamber. This generator 32 is more fully described in Patent No. 2,280,210, Glenn F. Zellhoefer, dated April 21, 1942.

'I'he strong solution pumped into the manifold 38 of the heat generator 32 is passed through the coils 36 and discharged into the inner receptacle 40. In this receptacle, maintained at elevated f temperatures by the steam jacket 34, the refrigerant separates from the solvent and the refrigerant vapors pass through an eliminator 52 to the upper portion 54 of the generator and thence through a conduit 56 to a condenser 58. The temperature of the condenser 58 is controlled by cooling coils 60 which are supplied with water in a manner to be hereinafter more fully described.

'I'he refrigerant vapors condensed in the cona dehydrator 64, and conduit 66 to the outer jacket of a heat exchanger 68. From the heat exchanger 68 the liquid passes through conduit to a float-controlled valve 12 positioned in a housing 13.

The float-operated valve 12 serves as an expansion valve for the liquid refrigerant; thus the liquid passing through the valve 12 passes from a. high pressure zone in the conduit 10 to a low pressure zone within the valve chamber 84. A portion of the liquid refrigerant vaporizes, resulting in cooling. and the cold vaporsI and liquid refrigerant mixture passes from the valve chamber 84 through conduit 86 to the chilling chamber 14. 'I'he liquid refrigerant passing into the chiller is maintained at a constant level in the chiller 14 by controlled addition of refrigerant thereto as regulated by means of the float-controlled valve 12. The float valve 12 is operated by the float 16 maintained at about the same level as the liquid in the chiller 14 through the equalizing lines 18vand 80.

A medium to be cooled enters chiller 14 through a conduit 19, passing through coils 82 submerged in the liquid refrigerant and out through a conduit 8|, for use as desired. The fluid passing through the coils 82 is in heat-exchange relationship with the refrigerant in the chiller 14, and the refrigerant is thereby caused to boil by the exchange of heat from the relatively warm fluid in the coils 82 to the refrigerant. The level of iliquid refrigerant in the chiller may be adjusted as desired, but it is preferable to have it extend denser 58 pass as a liquid through conduit 62,

assur? chiller through which the nuid to be cooled is circulated. 'I'he boiling o1' the refrigerant vapors from the body of liquid refrigerant causes a chill- 1118 of the coils 82, and the vapors escape from the top of the chiller 14 through conduit 80 to the upper portion of the absorber I4, wherein the refrigerant vapors are again contacted with the solvent for re-absorption and recirculation through the heat exchanger 28 and the generator 32, as hereinbefore described.

'Ihe weak solvent solution from which the refrigerant has been distilled in the heater or generator 32 drops to the bottom of the inner chamber 40 of the generator and passes out thereof by gravity flow through conduit 92 into a sump 94, the sump being provided with a vent 86 leading to the upper portion 54 of the generator 32. From the bottom of the sump 84 the weak solution passes by gravity now through conduit 88 to the heat exchanger 28, where the heat of the weak solution is transferred to the strong solution leaving the absorber and entering the heater in counterflow arrangement on the heat exchanger. 'I'he preheating of the strong solution prior to the passage thereof into the heater effects an economy in steam consumption in the heater. From the heat exchanger 28, the weak solution is recirculated to the absorber 'I4 through conduits |02, the other half of the pump I6, conduit |04, strainer |08, and conduit |06. The pump serves to maintain a constant head of solvent in a nozzle bank |I0 through which the weak solution is pumped into the absorber 'I4 onto watercooled coils II2. The refrigerant vapors are reabsorbed by the weak solvent, and the solvent containing the absorbed refrigerant vapors is then withdrawn from the bottom of the absorber I4 through the sump I2 and recycled as hereinbefore described.

The cooling coils II2 are provided in the absorber I4 for the purpose of dissipating the heat of solution evolved when the gaseous refrigerant is re-absorbed by the solvent. The coils further function to provide a means for distributing the solvent in thin films over the surface of the interior of the absorber so that the refrigerant may be readily absorbed by the solvent.

'I'he condenser 58 is also provided with fluidcooled coils in order to cool the gaseous refrigerant from the generator to the point of liquefaction at the relatively high pressure in that portion of the system. It is important that the pressure on the high pressure side of the system be maintained sufficiently great to cause optimum flow of the refrigerant through the system, and further to permit the weak liquor to be forced from the bottom of the chamber 40 in the heater 32 back through the heat exchanger 28 and into the absorber I4. In order to effect this control and to maintain the condensate at a temperature so that proper pressure differentials will be maintained, the volume of cooling fluid passing through the coil 60 of the condenser 58 is automatically regulated by valve I I4 which in turn is operated by the pressures within the condenser 58. A detail view of the valve is shown in Fig. 2 and will be hereinafter more fully described.

Fluid such as water is passed from a suitable source of supply, such as a water tower, through conduit II6, through the coils II2 of the absorber I4, and through conduit I I8 to the twoway valve II4. The valve II4 is pressure operated and so constructed that increased pressure of the refrigerant within the condenser 56, re-

. ating valve IH through the pressure line |66 in the opposite direction, causing more of the water to by-pass the condenser and escape from the system through conduit |22. By this means the temperature within the condenser is accuratelyv controlled, which, in turn, controls the pressure on the weak solventsolution within the container l0 oi' the heater 82, thereby insuring its proper return through the heat exchanger 28 to the absorber I4. Constant pressures and temperatures are therefore obtainable in the coni denser even through the temperature of the cooling fluid may be varied over a wide range.

The valve IN is automatically operated by the fluid pressure in the condenser 58, and is shown in detail in Fig. 2 of the'drawings to which reference will now be had. The valve construction comprises a pressure chamber |58 within a housing |51, the housing also containing a pressureoperated mechanism including a bellows |58, a plunger |60, a compression spring |62, and a guide spring |65.

The lpressure chamber |56 is in direct connection with the vlapor chamber of the condenser 58 by means ofthe pressure conduit |66. Thus, when pressure is applied through the conduit |66, the plunger |60 is pushed upwardly against the compression of' spring |62 to extend out of the ,pressure chamber a greater distance. As shown in Fig. 2, the housing |51 for the pressure chamber |56 is secured to the outside of a conduit |61 within which are pivoted a pair oi` butterfly valves |68 and |10. As shown, these butterfly valves are reciprocably secured to each other by a rod |12 which extends through holes positioned in projections located on the ends of each of the butterily valves so that when one is operated, the other one will be also. 'I'he length of the rod |12 is so adjusted that the valve |68 is brought into the full open position when the valve is in the full closed position, and vice versa.

The valves |68 and |10 are operated by the plunger |60 by means of a lever |16 pivotally mounted at one end thereof to the outside of lthe conduit |61. The upper end of the plunger |60, which extends outwardly of a packing gland |6| is pivotaly secured to a central portion of the lever |16, the free end of the lever having a slot |16 positioned therein which is adapted to receive the end oi a crank bar |18. The crank bar |18 is mounted on the same shaft as, and rotates with, the butterfly valve |68, whereby raising of the crank bar |18 from the .position shown in the drawing will close the butterfly valve |66. From the above, it is clear that, when the pressure is increased within the pressure chamber |55, the plunger |60 is raised, which in turn pivots the lever |16 upwardly, causing the butterfly valve |68 to close and the butterfly valve |10 to open. Contnariwise, when the pressure in the pressure chamber |56 drops, the reverse occurs.

As hereinabove explained, it is desirable that an optimum pressure be maintained within the condenser 58 in order to maintain proper pressure differentials in the system land to insure the return of the weak solvent from the inner chamber 40 of the heater 32 back to the absorber I4, In

6 order that this pressure may be regulated, the temperature is controlled in the condenser by the rate at which the cooling fluid is passed therethrough. The two-way valve H4 may be adjusted so that when the pressure becomes greater than the desired optimum. the valve |10 opens 'and valve |88 closes, whereby a portion of the cooling water is passed through the conduit |20 to the condenser coils 60, automatically cutting down the amount oi' cooling fluid by-passing the ,condenser through the conduit |22. Ii the condenser gets too cold, the pressure in the chamber |58 will be reduced and the amount of fluid by-passing the condenser will be increased.

It will be clear from the above description of the arrangement and operation of the valve ||4 that the temperature and pressures within the condenser will'always be held at a constant value, v

through and only smaller amounts will be b passed.

The chiller unit 14 and the float valve for controlling the ow of refrigerant from the condenser 58 are described in detail in my above re- .ferred to prior application, Serial No. 350,993, and no further description of these portions of the apparatus is thought to be necessary in this application.

While a particular embodiment of this invention is shown above, it will be understood, of

course, that the invention is not to be limited .cooling fluid through said coils, a valve associated with said last-mentioned means for regulating the flow of said fluid into said coils, and a pressure-responsive mechanismV for operating said valve in accordance with the vapor pressure within said condenser whereby the temperature and pressure of the refrigerant in said condenser is regulated to a predetermined value.

2; In an absorption type refrigerating apparatus of the character described, the combination of a heater, a condenser.. cooling coils for the condenser, means for passing a cooling fluid through said coils, a valve associated with said last-mentioned means for regulating the flow of said fluid into said coils, and a pressure-responsive mechanism for operating said valve d n accordance-with the vapor pressure within said condenser whereby the temperature of the refrigerant in said condenser is regulated to a predetermined value and whereby the pressure of refrigerant vapors within said heater is maintained substantially constant.

3. In an absorption type refrigerating apparatus of the character described, the combination of a heater, a condenser, cooling coils for the condenser, conduits for directing a cooling fluid to and from said coils, a yby-pass valve associated with said conduits for regulating the flow of said fluid to said coils, and a pressureresponsive mechanism for operating said by-pass valve lin accordance with the vapor pressure l V:nieuwe 'pass valve for passing the fluid from said absorber coils to said condenser coils, and means for discharging said fluid from the condenser l coils, said by-pass valve including va pressureresponsive mechanism for operating said valve in accordance with the vapor pressure within said condenser whereby a portion of said cooling fluid passes through said valve to control the temperature within said condenser to a predetermined value whereby a predetermined constant pressure of refrigerant vapor is maintained in said condenser and said heater.

5. In an absorption type refrigerating apparatus of the character described, the combination of a heater, a condenser, .cooling coils for the condenser, conduits for directing a cooling fluid to and from said coils for controlling the temperature in said condenser, and a iiorw regulating means for controlling the amount of iiow of cooling fluid through said cooling coils, said flow regulator means comprising a valve in the conduit for directing cooling uid into the cooling coils, a by-pass valve, common actuating means for alternately opening and closing said valves, and a pressure-responsive mechanism for operating said actuating means in accordance with the pressure within said condenser. Y

6. In an absorption type refrigerating apparatus of the character described. the combination of a heater, a condenser, cooling coils for the condenser, conduits for directing a cooling duid to and from said coils, a chamber having an inflow orifice and a pair of outflow orifices associated with said conduits, a |pair of valves in said chamber positioned between said inflow orifice and each of said outflow orifices to controithe flow of cooling fluid through the chamber from the innow orifice to said outflow orifices. and pressure-responsive means responsive to the vapor pressure within said condenser for operating `said valves to eiiect the opening of `one and the simultaneous closing of the other, whereby the temperature of the refrigerant in said condenser is regulated to a predetermined value and the pressure of refrigerant .vapors Within said heater is maintained substantially constant.

7. In an absorption type refrigerating apparatus of the character described, the combination of an absorber, cooling coils in the absorber,

a heater, a condenser, cooling coils in the condenser, means for passing a cooling fluid into said absorfber coils, means including a by-pass valve for passing the fluid from said absorber coils to said condenser coils, and means for discharging said fluid from the condenser coils, said by-pass valve including a chamber having an inflow orifice and a. pair of outflow orices, a pair of Valve members positioned between said inflow orice and each of said outfiorw orices, and means for operating said valve in response to the vapor pressure within said condenser to open one valve member and simultaneously close the other whereby a portion of said cooling fluid passes through said valve to saidcondenser to control the temperature thereof and a predetermined constant pressure of refrigerant vapor is maintained in said condenser and said heater.

WALTER W. WILLIAMS.

REFERENCES CITED The following references are of record in the i'lle of this patent:

UNITED STATES PATENTS Number Name Date 1,937,565 Grifiiths Dec. 5, 1933 1,992,048 Temple Feb. 18, 1935 2,042,694 Zellhoefer June 2, 1936 2,298,924 Bichowsky Oct. 13, 1942 2,365,797 Bichowsky Dec. 26, 1944 2,378,177 Bichowsky June 12, 1945 

